OBJECTIVES: A. Overall objectives of Grant AM-19245 are: 1. To determine local toxicity of agents for physical dissolution of retained common duct stones. 2. To characterize the enterohepatic circulation of nor-chenodeoxycholic acid, and to define its effect on biliary lipid composition. 3. To define significance of defective sulfation of lithocholate for chenodeoxycholate toxicity in the rhesus monkey. B. Goals for the current year: 1. To characterize the enterohepatic circulation of nor-chenodeoxycholic acid. 2. To complete determination of local toxicity of cholate infusions via T-tube. 3. To evaluate new, non-toxic agents.